System and process for inhibitor injection

ABSTRACT

A method for introducing inhibitor into a fluid to be treated by forming a dispersion comprising droplets, particles, or gas bubbles of inhibitor dispersed in a continuous phase of a carrier, wherein forming the dispersion comprises subjecting a mixture of the inhibitor and the carrier to a shear rate of greater than about 20,000 s −1  in a high shear device comprising at least one generator comprising a rotor and a complementarily-shaped stator, wherein the rotor and the stator each comprise grooves, and wherein the grooves of the stator and the grooves of the rotor of each generator are disposed in alternating directions, and using at least a portion of the dispersion to inhibit corrosion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. Ser. No.13/560,457 filed on Jul. 27, 2012, which application is a continuationapplication of U.S. Ser. No. 12/142,544 filed on Jun. 19, 2008 (now U.S.Pat. No. 8,282,266, issued Oct. 9, 2012), which application claims thebenefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent ApplicationNo. 60/946,463 filed Jun. 27, 2007. The disclosure of each applicationis hereby incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

TECHNICAL FIELD

The present invention relates generally to inhibitor injection. Moreparticularly, the present invention relates to a system and process forinhibitor injection comprising high shear dispersing.

BACKGROUND

An inhibitor is a chemical agent added to a fluid system to inhibit orprevent an undesirable reaction from occurring within the fluid or withthe materials present in the surrounding environment. Numerousinhibitors are used in the petroleum, petrochemical, and chemicalindustries. For example, corrosion is recognized as a serious problem inthe development of geoenergy sources, including oil and natural gasreserves, geothermal, and geopressured systems and leads to great coststo the industry every year. Corrosion problems are greatly aggravated bythe presence of acid gases such as hydrogen sulfide and carbon dioxide,and by the co-production of brine solutions. As an alternative to theuse of high alloy components which are expensive in relation to commoncarbon steels, a range of corrosion inhibitors have been researched formitigating the occurrence of corrosion in the production and servicingof oil and gas wells. The use of inhibitors may permit the use ofregular carbon steel components rather than more expensive alloys.Corrosion inhibitors are injected into process streams (for example inacidizing treatments) to inhibit corrosion of metal equipment andwellbore components and are generally carried in liquid steams tocontact inner surfaces and other contact surfaces of plant equipment. Acorrosion inhibitor may create a protective film or passivation layer ona metal surface and thus inhibit corrosion by acidic components in aprocess stream. For example, drill pipe may be coated with amine film toarrest corrosion of the pipe on contact with air.

Corrosion problems may be greater when production from deeper formationsis pursued. Production of deep, sour gas reserves and deep geopressuredzones may involve high bottom hole temperatures (as high as 200° C.) andpressures (up to 140 MPa). Additionally, the produced gas may containprimarily acid gases such as carbon dioxide and hydrogen sulfide andminor amounts (as low as about 20%) of desired hydrocarbon such asmethane. The acid gases may be present along with high salinity sodiumchloride brine in the producing formations, with chloride contentsranging as high as several moles per kilogram of water. Lower pH fluidsare generally more corrosive, and, with pH values which may be as low as2 to 3, deep downhole fluids may be very corrosive.

In the case of geopressured and geothermal systems, the acid gas contentis typically much lower. However, these systems may be characterized byhigh salinity brines (as much as 150,000 ppm of chloride, for example)and high bottom hole temperatures (up to 310° C.). These fluids may havehigher pH values than those estimated for deep sour gas systems,generally in the range of 4 to 5, however higher bottom holetemperatures may increase the potential for corrosion in such systems.

Conditions such as high acid gas (e.g., hydrogen sulfide) concentration,severe scale deposition, ice or hydrate formation, and flow reductionmay be inhibited by injection of inhibitors. A challenge to theapplication of inhibitors is that inhibitors are typically used in smallamounts as low as parts per million and care must be taken to adequatelyintroduce the small quantity such that the inhibitor is uniformlydispersed in the fluid to be treated.

Accordingly, there is a need in industry for improved systems andprocesses for injecting inhibitors into fluids whereby increased processfluid throughput, increased degree of inhibition of undesirablecomponent or condition, and/or the use of reduced amounts of generallycostly inhibitor may be achieved.

SUMMARY

A high shear system and process for enhancing inhibitor injection aredisclosed. The high shear process may make possible a reduction in masstransfer limitations of conventional inhibitor injection processes,thereby increasing the inhibitor efficiency and potentially enabling areduction in required amount of inhibitor, an increasedelimination/prevention of undesirable components (for example,corrodents, ice, scale), and/or an increase in throughout. The systemand process employ an external high shear mechanical reactor to provideenhanced conditions for inhibition. In some embodiments, theseconditions result in accelerated chemical reactions between multiphasereactants. In embodiments, these enhanced conditions result in enhancedinteraction between liquid components. The high shear device may be anexternal pressurized high shear device that may permit reduction in theamount of inhibitor required.

A method is provided for introducing inhibitor into a fluid to betreated by forming a dispersion comprising droplets, particles, or gasbubbles of the inhibitor dispersed in a continuous phase of a carrier,wherein the droplets, particles, or gas bubbles have a mean diameter ofless than 5 μm, and wherein either the carrier is the fluid to betreated or the method further comprises introducing the dispersion intothe fluid to be treated. The inhibitor may be selected from corrosioninhibitors, transport-enhancing inhibitors, scale inhibitors, hydrateinhibitors, ice-formation inhibitors, and combinations thereof. Inembodiments, the dispersion is formed from liquid or solid inhibitor.Alternatively, the dispersion is formed from a gaseous inhibitor.Droplets or gas bubbles of inhibitor may have a mean diameter of lessthan 1 μm, or less than or equal to 400 nm. In embodiments, the fluid tobe treated comprises boiler feedwater or a transport stream comprisinghydrocarbons. The carrier may comprise at least a portion of the fluidto be treated. The carrier may comprise LPG. Forming the dispersion maycomprise subjecting a mixture of the inhibitor and the carrier to ashear rate of greater than about 20,000 s⁻¹. Forming the dispersion maycomprise contacting the inhibitor and the carrier in a high sheardevice, wherein the high shear device comprises at least one rotor, andwherein the at least one rotor is rotated at a tip speed of at least22.9 m/s (4,500 ft/min) during formation of the dispersion. The highshear device may produce a local pressure of at least about 1034.2 MPa(150,000 psi) at the tip of the at least one rotor. In applications, theenergy expenditure of the high shear device is greater than 1000 wattsper cubic meter of fluid therein during dispersion formation.

Also disclosed is a method for introducing inhibitor into a fluid to betreated by subjecting a fluid mixture comprising inhibitor and a carrierto a shear rate greater than 20,000 s⁻¹ in a high shear device toproduce a dispersion of inhibitor in a continuous phase of the carrier;wherein either the carrier is the fluid to be treated or the methodfurther comprises introducing the dispersion into the fluid to betreated. The dispersion may comprise particles, droplets, or gas bubblesof inhibitor dispersed in the continuous phase, wherein the averagediameter of the droplets, particles, or gas bubbles is less than about 5μm. The dispersion may be stable for at least about 15 minutes atatmospheric pressure. In some applications, the high shear devicecomprises at least two generators, each generator comprising a statorand a complementarily-shaped rotor.

Also disclosed is a system for inhibiting a component in a fluid, thesystem comprising at least one high shear mixing device comprising atleast one generator comprising a rotor and a stator separated by a sheargap, wherein the shear gap is the minimum distance between the rotor andthe stator, and wherein the high shear mixing device is capable ofproducing a tip speed of the rotor of greater than 22.9 m/s (4,500ft/min), and a pump configured for delivering a mixture of a carrier andan inhibitor to the high shear mixing device. The component to beinhibited may be ice, scale, hydrates, acidic chemicals, andcombinations thereof. The system may further comprise a flow line orvessel configured for receiving the dispersion from the high sheardevice. The vessel may be a boiler. The at least one high shear mixingdevice may be configured for producing a dispersion of the inhibitor ina continuous phase comprising the carrier, wherein the dispersion has amean bubble, particle, or droplet diameter of less than 5 μm. Inapplications, the at least one high shear mixing device is capable ofproducing a tip speed of the rotor of at least 40.1 m/s (7,900 ft/min).The shear gap of the at least one generator may be in the range of fromabout 0.02 mm to about 5 mm. The at least one high shear device maycomprise at least two generators. In applications, the shear rateprovided by one generator is greater than the shear rate provided byanother generator. The system may comprise at least two high shearmixing devices.

Embodiments of the disclosure pertain to a method for introducinginhibitor into a fluid to be treated that may include forming adispersion comprising droplets, particles, or gas bubbles of inhibitordispersed in a continuous phase of a carrier. Forming the dispersion mayinclude subjecting a mixture of the inhibitor and the carrier to a shearrate of greater than about 20,000 s⁻¹. The method may include using atleast a portion of the dispersion to inhibit corrosion. Using thedispersion to inhibit corrosion may include treating an inner flow linesurface. Using the dispersion may also include injecting the dispersioninto a geothermal system, wherein the carrier comprises at least aportion of the fluid to be treated.

In some aspects, the droplets, particles, or gas bubbles may have a meandiameter of less than 5 μm, while in other aspects the mean diameter maybe less than 1 μm. The dispersion may be formed in a high shear device.In addition, the fluid to be treated may include boiler feedwater or atransport stream comprising hydrocarbons. The method may includeinjecting the dispersion into a gas well. In some aspects, thedispersion may be formed with a liquid, solid, or gaseous inhibitor.

Forming the dispersion may include contacting the inhibitor and thecarrier in a high shear device. The high shear device may have at leastone rotor. In some aspects, the at least one rotor may be rotated at atip speed of at least 22.9 m/s (4,500 ft/min) during forming of thedispersion. In other aspects, the carrier may be LPG. The high sheardevice may produces a local pressure of at least about 1034.2 MPa(150,000 psi) at the tip of the at least one rotor.

Other embodiments of the disclosure pertain to a method for introducinginhibitor into a fluid to be treated that may include processing a fluidmixture comprising inhibitor and a carrier fluid in a high shear deviceto produce a dispersion of inhibitor in the carrier fluid; and using thedispersion to inhibit a component selected from the group consisting ofice, scale, hydrates, acidic chemicals, and combinations thereof. Usingthe dispersion may include treating a surface of a vessel or a flowline.

The dispersion may include particles, droplets, or gas bubbles ofinhibitor having an average diameter of the droplets, particles, or gasbubbles less than about 5 μm. The method may include receiving thedispersion into a boiler. The method may include operating the highshear device at a shear rate greater than 20,000 s⁻¹.

Yet other embodiments of the disclosure relate to a method forintroducing inhibitor into a fluid to be treated that may includeforming a dispersion comprising droplets, particles, or gas bubbles ofthe inhibitor dispersed in a carrier fluid, wherein the droplets,particles, or gas bubbles have a mean diameter of less than 5 μm;subjecting the dispersion to a shear rate greater than 20,000 s⁻¹ in ahigh shear device; and using the dispersion to treat a surface of a flowline or vessel.

In some aspects, the high shear device may include at least onegenerator having a rotor and a stator separated by a shear gap widththat is the minimum distance between the rotor and the stator. The highshear device may be configured to produce a tip speed of the rotor ofgreater than 22.9 m/s (4,500 ft/min). In other aspects, the high sheardevice may include a second generator further having a second stator anda second complementarily-shaped rotor. In yet other aspects, the rotorand the stator each comprise grooves disposed in alternating directions

The component may be selected from ice, scale, hydrates, acidicchemicals, and combinations thereof, and the vessel may be a boiler. Inembodiments, the high shear device may include a second generatorfurther having a second stator and a second complementarily-shapedrotor.

These and other embodiments and potential advantages will be apparent inthe following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of an inhibitor injection system according to anembodiment of the present disclosure comprising external high sheardispersing.

FIG. 2 is a longitudinal cross-section view of a multi-stage high sheardevice, as employed in an embodiment of the system.

NOTATION AND NOMENCLATURE

As used herein, the term “dispersion” refers to a liquefied mixture thatcontains at least two distinguishable substances (or “phases”) that willnot readily mix and dissolve together. As used herein, a “dispersion”comprises a “continuous” phase (or “matrix”), which holds thereindiscontinuous droplets, bubbles, and/or particles of the other phase orsubstance. The term dispersion may thus refer to foams comprising gasbubbles suspended in a liquid continuous phase, emulsions in whichdroplets of a first liquid are dispersed throughout a continuous phasecomprising a second liquid with which the first liquid is immiscible,and continuous liquid phases throughout which solid particles aredistributed. As used herein, the term “dispersion” encompassescontinuous liquid phases throughout which gas bubbles are distributed,continuous liquid phases throughout which solid particles (e.g., solidcatalyst) are distributed, continuous phases of a first liquidthroughout which droplets of a second liquid that is substantiallyinsoluble in the continuous phase are distributed, and liquid phasesthroughout which any one or a combination of solid particles, immiscibleliquid droplets, and gas bubbles are distributed.

Hence, a dispersion can exist as a homogeneous mixture in some cases(e.g., liquid/liquid phase), or as a heterogeneous mixture (e.g.,gas/liquid, solid/liquid, or gas/solid/liquid), depending on the natureof the materials selected for combination.

The term “inhibitor” is used herein to refer to any chemical compoundused to inhibit formation of an undesirable component in a fluid orinhibit an undesirable condition in a flow line or vessel or on acontact surface thereof. For the purposes of this disclosure, the term“inhibitor” includes conventional inhibitors, as well as chemicalcompounds, such as viscosity reducers, which may prevent an undesirablereduction of flow rate in a flow line.

The term “flow line” is used herein to indicate any vessel or line usedto transport, hold, or contact a fluid that contains a component to beinhibited via the inhibitor. The term “flow line” thus encompasses linessuch as piping and transport lines and vessels including withoutlimitation boilers, pumps, condensers, reflux drums, and reflux pumps.

DETAILED DESCRIPTION

Overview. The rate of chemical reactions involving liquids, gases andsolids depend on time of contact, temperature, and pressure. In caseswhere it is desirable to react two or more raw materials of differentphases (e.g., solid and liquid; liquid and gas; solid, liquid and gas),one of the limiting factors controlling the rate of reaction involvesthe contact time of the reactants. When reaction rates are accelerated,residence times may be decreased, thereby increasing obtainablethroughput. Enhancing contact via the use of high shear may permitincreased throughput and/or the use of a decreased amount of generallyexpensive inhibitor relative to conventional inhibitor injectionprocesses.

Contact time for the reactants is often controlled by mixing whichprovides contact with two or more reactants involved in a chemicalreaction. A system and process for inhibitor injection comprises anexternal high shear mechanical device to provide rapid contact andmixing of chemical ingredients in a controlled environment in thereactor/mixer device. A reactor assembly that comprises an external highshear device or mixer as described herein may decrease mass transferlimitations, and thereby allow an inhibition reaction to more closelyapproach kinetic limitations. In embodiments, the high shear device isused to form a dispersion of a gas in a liquid. In other embodiments,the high shear device is used to intimately mix two liquids, forexample, hydrocarbon and a liquid inhibitor. In embodiments, theinhibitor is a gas.

In embodiments, the inhibitor is a liquid. In applications, theinhibitor is a gas and is injected into a liquid carrier. In alternativeapplications, the inhibitor is a liquid and is injected into a liquidcarrier. In the case of homogeneous reactions, for example liquid/liquidreactions, enhanced mixing may increase the rate of inhibitionreaction(s) and may also homogenize the temperature within the reactionzone(s).

The disclosed high shear system and method may be incorporated intoconventional inhibitor injection processes, thereby enhancing inhibitionof an undesirable component or condition. For example, inhibitors may beadded to avoid the production of scale, corrosion (e.g., from hydrogensulfide, carbon dioxide, etc.), formation of ice, formation of gashydrates, and the like.

Other uses of the disclosed system and method will become apparent uponreading the disclosure and viewing the accompanying drawings. While thefollowing description will be given with respect to injection ofinhibitors via an injection line run alongside a pipeline to permitinjection of inhibitors or similar treatments, other embodiments areenvisioned. The embodiments described herein are exemplary only, and arenot intended to be limiting. For example, the high shear system andprocess may be used for the injection of disparate types and phases(e.g., gas or liquid) of inhibitors into various flow lines (i.e., linesor vessels).

System for Introduction of Inhibitor. A high shear inhibitor injectionsystem will now be described in relation to FIG. 1, which is a processflow diagram of an embodiment of a high shear system 100 forintroduction of inhibitor into a fluid to be treated. The basiccomponents of a representative system include external high shear mixingdevice (HSD) 40 and pump 5, and flow line 10. The term “flow line” isused herein to indicate any vessel or line used to transport or hold afluid that contains a component to be inhibited via the inhibitor. Theterm “flow line” thus encompasses lines such as piping and transportlines and vessels including without limitation boilers, pumps,condensers, reflux drums, and reflux pumps. As shown in FIG. 1, highshear device 40 is located external to flow line 10. Each of thesecomponents is further described in more detail below. Line 21 isconnected to pump 5 for introducing carrier fluid into HSD 40. Line 13connects pump 5 to HSD 40, and line 18 may connect HSD 40 to flow line10. Line 22 may be connected to line 13 for introducing inhibitor intoHSD 40. Alternatively, line 22 may be connected directly to an inlet ofHSD 40. Additional components or process steps may be incorporatedbetween flow line 10 and HSD 40, or ahead of pump 5 or HSD 40, ifdesired, as will become apparent upon reading the description of thehigh shear inhibitor injection process hereinbelow. For example, line 20may be connected to line 21 or line 13 from flow line 10, such thatfluid in flow line 10 may be used as carrier. Line 20 may be connectedto flow line 10 at a location 14 upstream of the position whereinhibition is required, for example, upstream of a location at whichconditions for scale formation or corrosion are predicted. Inembodiments, line 21 and line 20 are a single line connecting flow line10 and pump 5. Treated fluid may continue along flow line 10 downstreamthe intersection 16 of line 18 and flow line 10.

High Shear Mixing Device. External high shear mixing device (HSD) 40,also sometimes referred to as a high shear device or high shear mixingdevice, is configured for receiving an inlet stream, via line 13,comprising carrier fluid and inhibitor. Alternatively, HSD 40 may beconfigured for receiving the carrier fluid and the inhibitor viaseparate inlet lines (not shown). Although only one high shear device isshown in FIG. 1, it should be understood that some embodiments of thesystem may have two or more high shear mixing devices arranged either inseries or parallel flow. HSD 40 is a mechanical device that utilizes oneor more generator comprising a rotor/stator combination, each of whichhas a gap between the stator and rotor. The gap between the rotor andthe stator in each generator set may be fixed or may be adjustable. HSD40 is configured in such a way that it is capable of producing submicronand micron-sized bubbles or droplets of inhibitor in a continuous phasecomprising the carrier flowing through the high shear device. The highshear device comprises an enclosure or housing so that the pressure andtemperature of the fluid therein may be controlled.

High shear mixing devices are generally divided into three generalclasses, based upon their ability to mix fluids. Mixing is the processof reducing the size of particles or inhomogeneous species within thefluid. One metric for the degree or thoroughness of mixing is the energydensity per unit volume that the mixing device generates to disrupt thefluid particles. The classes are distinguished based on delivered energydensities. Three classes of industrial mixers having sufficient energydensity to consistently produce mixtures or emulsions with particlesizes in the range of submicron to 50 microns include homogenizationvalve systems, colloid mills and high speed mixers. In the first classof high energy devices, referred to as homogenization valve systems,fluid to be processed is pumped under very high pressure through anarrow-gap valve into a lower pressure environment. The pressuregradients across the valve and the resulting turbulence and cavitationact to break-up any particles in the fluid. These valve systems are mostcommonly used in milk homogenization and can yield average particlesizes in the submicron to about 1 micron range.

At the opposite end of the energy density spectrum is the third class ofdevices referred to as low energy devices. These systems usually havepaddles or fluid rotors that turn at high speed in a reservoir of fluidto be processed, which in many of the more common applications is a foodproduct. These low energy systems are customarily used when averageparticle sizes of greater than 20 microns are acceptable in theprocessed fluid.

Between the low energy devices and homogenization valve systems, interms of the mixing energy density delivered to the fluid, are colloidmills and other high speed rotor-stator devices, which are classified asintermediate energy devices. A typical colloid mill configurationincludes a conical or disk rotor that is separated from a complementary,liquid-cooled stator by a closely-controlled rotor-stator gap, which iscommonly between 0.025 mm to 10 mm (0.001-0.40 inch). Rotors are usuallydriven by an electric motor through a direct drive or belt mechanism. Asthe rotor rotates at high rates, it pumps fluid between the outersurface of the rotor and the inner surface of the stator, and shearforces generated in the gap process the fluid. Many colloid mills withproper adjustment achieve average particle sizes of 0.1-25 microns inthe processed fluid. These capabilities render colloid mills appropriatefor a variety of applications including colloid and oil/water-basedemulsion processing such as that required for cosmetics, mayonnaise, orsilicone/silver amalgam formation, to roofing-tar mixing.

Tip speed is the circumferential distance traveled by the tip of therotor per unit of time. Tip speed is thus a function of the rotordiameter and the rotational frequency. Tip speed (in meters per minute,for example) may be calculated by multiplying the circumferentialdistance transcribed by the rotor tip, 2πR, where R is the radius of therotor (meters, for example) times the frequency of revolution (forexample revolutions per minute, rpm). A colloid mill, for example, mayhave a tip speed in excess of 22.9 m/s (4500 ft/min) and may exceed 40m/s (7900 ft/min). For the purpose of this disclosure, the term ‘highshear’ refers to mechanical rotor stator devices (e.g., colloid mills orrotor-stator dispersers) that are capable of tip speeds in excess of 5.1m/s (1000 ft/min) and require an external mechanically driven powerdevice to drive energy into the stream of products to be reacted. Forexample, in HSD 40, a tip speed in excess of 22.9 m/s (4500 ft/min) isachievable, and may exceed 40 m/s (7900 ft/min). In some embodiments,HSD 40 is capable of delivering at least 300 L/h at a tip speed of atleast 22.9 m/s (4500 ft/min).

The power consumption may be about 1.5 kW. HSD 40 combines high tipspeed with a very small shear gap to produce significant shear on thematerial being processed. The amount of shear will be dependent on theviscosity of the fluid in HSD 40. Accordingly, a local region ofelevated pressure and temperature is created at the tip of the rotorduring operation of the high shear device. In some cases the locallyelevated pressure is about 1034.2 MPa (150,000 psi). In some cases thelocally elevated temperature is about 500° C. In some cases, these localpressure and temperature elevations may persist for nano or picoseconds.

An approximation of energy input into the fluid (kW/L/min) can beestimated by measuring the motor energy (kW) and fluid output (L/min).As mentioned above, tip speed is the velocity (ft/min or m/s) associatedwith the end of the one or more revolving elements that is creating themechanical force applied to the fluid. In embodiments, the energyexpenditure of HSD 40 is greater than 1000 watts per cubic meter offluid therein. In embodiments, the energy expenditure of HSD 40 is inthe range of from about 3000 W/m³ to about 7500 W/m³.

The shear rate is the tip speed divided by the shear gap width (minimalclearance between the rotor and stator). The shear rate generated in HSD40 may be in the greater than 20,000 s⁻¹. In some embodiments the shearrate is at least 40,000 s⁻¹. In some embodiments the shear rate is atleast 100,000 s⁻¹. In some embodiments the shear rate is at least500,000 s⁻¹. In some embodiments the shear rate is at least 1,000,000s⁻¹. In some embodiments the shear rate is at least 1,600,000 s⁻¹. Inembodiments, the shear rate generated by HSD 40 is in the range of from20,000 s⁻¹ to 100,000 s⁻¹. For example, in one application the rotor tipspeed is about 40 m/s (7900 ft/min) and the shear gap width is 0.0254 mm(0.001 inch), producing a shear rate of 1,600,000 s⁻¹. In anotherapplication the rotor tip speed is about 22.9 m/s (4500 ft/min) and theshear gap width is 0.0254 mm (0.001 inch), producing a shear rate ofabout 901,600 s⁻¹.

HSD 40 is capable of highly dispersing the inhibitor into a continuousphase comprising the carrier, with which it would normally beimmiscible. In some embodiments, HSD 40 comprises a colloid mill.Suitable colloidal mills are manufactured by IKA® Works, Inc.Wilmington, N.C. and APV North America, Inc. Wilmington, Mass., forexample. In some instances, HSD 40 comprises the Dispax Reactor® of IKA®Works, Inc.

The high shear device comprises at least one revolving element thatcreates the mechanical force applied to the fluid therein. The highshear device comprises at least one stator and at least one rotorseparated by a clearance. For example, the rotors may be conical or diskshaped and may be separated from a complementarily-shaped stator. Inembodiments, both the rotor and stator comprise a plurality ofcircumferentially-spaced teeth. In some embodiments, the stator(s) areadjustable to obtain the desired shear gap between the rotor and thestator of each generator (rotor/stator set). Grooves between the teethof the rotor and/or stator may alternate direction in alternate stagesfor increased turbulence. Each generator may be driven by any suitabledrive system configured for providing the necessary rotation.

In some embodiments, the minimum clearance (shear gap width) between thestator and the rotor is in the range of from about 0.025 mm (0.001 inch)to about 3 mm (0.125 inch). In certain embodiments, the minimumclearance (shear gap width) between the stator and rotor is about 1.5 mm(0.06 inch). In certain configurations, the minimum clearance (sheargap) between the rotor and stator is at least 1.7 mm (0.07 inch). Theshear rate produced by the high shear device may vary with longitudinalposition along the flow pathway. In some embodiments, the rotor is setto rotate at a speed commensurate with the diameter of the rotor and thedesired tip speed. In some embodiments, the high shear device has afixed clearance (shear gap width) between the stator and rotor.Alternatively, the high shear device has adjustable clearance (shear gapwidth).

In some embodiments, HSD 40 comprises a single stage dispersing chamber(i.e., a single rotor/stator combination, a single generator). In someembodiments, high shear device 40 is a multiple stage inline disperserand comprises a plurality of generators. In certain embodiments, HSD 40comprises at least two generators. In other embodiments, high sheardevice 40 comprises at least 3 high shear generators. In someembodiments, high shear device 40 is a multistage mixer whereby theshear rate (which, as mentioned above, varies proportionately with tipspeed and inversely with rotor/stator gap width) varies withlongitudinal position along the flow pathway, as further describedherein below.

In some embodiments, each stage of the external high shear device hasinterchangeable mixing tools, offering flexibility. For example, the DR2000/4 Dispax Reactor® of IKA® Works, Inc. Wilmington, N.C. and APVNorth America, Inc. Wilmington, Mass., comprises a three stagedispersing module. This module may comprise up to three rotor/statorcombinations (generators), with choice of fine, medium, coarse, andsuper-fine for each stage. This allows for creation of dispersionshaving a narrow distribution of the desired bubble or droplet size(e.g., gas bubbles or liquid droplets of inhibitor). In someembodiments, each of the stages is operated with super-fine generator.In some embodiments, at least one of the generator sets has arotor/stator minimum clearance (shear gap width) of greater than about 5mm (0.2 inch). In alternative embodiments, at least one of the generatorsets has a minimum rotor/stator clearance of greater than about 1.7 mm(0.07 inch).

Referring now to FIG. 2, there is presented a longitudinal cross-sectionof a suitable high shear device 200. High shear device 200 of FIG. 2 isa dispersing device comprising three stages or rotor-statorcombinations. High shear device 200 is a dispersing device comprisingthree stages or rotor-stator combinations, 220, 230, and 240. Therotor-stator combinations may be known as generators 220, 230, 240 orstages without limitation. Three rotor/stator sets or generators 220,230, and 240 are aligned in series along drive shaft 250.

First generator 220 comprises rotor 222 and stator 227. Second generator230 comprises rotor 223, and stator 228. Third generator 240 comprisesrotor 224 and stator 229. For each generator the rotor is rotatablydriven by input 250 and rotates about axis 260 as indicated by arrow265. The direction of rotation may be opposite that shown by arrow 265(e.g., clockwise or counterclockwise about axis of rotation 260).Stators 227, 228, and 229 may be fixably coupled to the wall 255 of highshear device 200.

As mentioned hereinabove, each generator has a shear gap width which isthe minimum distance between the rotor and the stator. In the embodimentof FIG. 2, first generator 220 comprises a first shear gap 225; secondgenerator 230 comprises a second shear gap 235; and third generator 240comprises a third shear gap 245. In embodiments, shear gaps 225, 235,245 have widths in the range of from about 0.025 mm to about 10 mm.Alternatively, the process comprises utilization of a high shear device200 wherein the gaps 225, 235, 245 have a width in the range of fromabout 0.5 mm to about 2.5 mm. In certain instances the shear gap widthis maintained at about 1.5 mm. Alternatively, the width of shear gaps225, 235, 245 are different for generators 220, 230, 240. In certaininstances, the width of shear gap 225 of first generator 220 is greaterthan the width of shear gap 235 of second generator 230, which is inturn greater than the width of shear gap 245 of third generator 240. Asmentioned above, the generators of each stage may be interchangeable,offering flexibility. High shear device 200 may be configured so thatthe shear rate will increase stepwise longitudinally along the directionof the flow 260.

Generators 220, 230, and 240 may comprise a coarse, medium, fine, andsuper-fine characterization. Rotors 222, 223, and 224 and stators 227,228, and 229 may be toothed designs. Each generator may comprise two ormore sets of rotor-stator teeth. In embodiments, rotors 222, 223, and224 comprise more than 10 rotor teeth circumferentially spaced about thecircumference of each rotor. In embodiments, stators 227, 228, and 229comprise more than ten stator teeth circumferentially spaced about thecircumference of each stator. In embodiments, the inner diameter of therotor is about 12 cm. In embodiments, the diameter of the rotor is about6 cm. In embodiments, the outer diameter of the stator is about 15 cm.In embodiments, the diameter of the stator is about 6.4 cm. In someembodiments the rotors are 60 mm and the stators are 64 mm in diameter,providing a clearance of about 4 mm. In certain embodiments, each ofthree stages is operated with a super-fine generator, comprising a sheargap of between about 0.025 mm and about 4 mm.

High shear device 200 is configured for receiving at inlet 205 a fluidmixture from line 13. The mixture comprises inhibitor as the dispersiblephase and carrier fluid as the continuous phase. Feed stream enteringinlet 205 is pumped serially through generators 220, 230, and then 240,such that product dispersion is formed. Product dispersion exits highshear device 200 via outlet 210 (and line 18 of FIG. 1). The rotors 222,223, 224 of each generator rotate at high speed relative to the fixedstators 227, 228, 229, providing a high shear rate. The rotation of therotors pumps fluid, such as the feed stream entering inlet 205,outwardly through the shear gaps (and, if present, through the spacesbetween the rotor teeth and the spaces between the stator teeth),creating a localized high shear condition. High shear forces exerted onfluid in shear gaps 225, 235, and 245 (and, when present, in the gapsbetween the rotor teeth and the stator teeth) through which fluid flowsprocess the fluid and create product dispersion. Product dispersionexits high shear device 200 via high shear outlet 210 (and line 18 ofFIG. 1).

The product dispersion has an average droplet or gas bubble size lessthan about 5 μm. In embodiments, HSD 40 produces a dispersion having amean droplet or bubble size of less than about 1.5 μm. In embodiments,HSD 40 produces a dispersion having a mean droplet or bubble size ofless than 1 μm; preferably the droplets or bubbles are sub-micron indiameter. In certain instances, the average droplet or bubble size isfrom about 0.1 μtm to about 1.0 μm. In embodiments, HSD 40 produces adispersion having a mean droplet or bubble size of less than 400 nm. Inembodiments, HSD 40 produces a dispersion having a mean droplet orbubble size of less than 100 nm. The dispersion may be capable ofremaining dispersed at atmospheric pressure for at least about 15minutes.

In certain instances, high shear device 200 comprises a Dispax Reactor®of IKA® Works, Inc. Wilmington, N.C. and APV North America, Inc.Wilmington, Mass. Several models are available having variousinlet/outlet connections, horsepower, tip speeds, output rpm, and flowrate. Selection of the high shear device will depend on throughputrequirements and desired particle, droplet or bubble size in dispersionin line 18 (FIG. 1) exiting outlet 210 of high shear device 200. IKA®model DR 2000/4, for example, comprises a belt drive, 4M generator, PTFEsealing ring, inlet flange 25.4 mm (1 inch) sanitary clamp, outletflange 19 mm (¾ inch) sanitary clamp, 2 HP power, output speed of 7900rpm, flow capacity (water) approximately 300-700 L/h (depending ongenerator), a tip speed of from 9.4-41 m/s (1850 ft/min to 8070 ft/min).

Flow Line. Flow line 10 is any line or vessel in which inhibition of anundesirable component or condition is desired. For instance, asindicated in the embodiment of FIG. 1, flow line 10 may be a transportpipeline. Such a pipeline may be used for transport of hydrocarbonstreams comprising water and acid gases. In some applications, HSD 40 ispositioned inline on flow line 10 such that the entirety of the fluid inflow line 10 is passed through one or more high shear devices. Inembodiments, the entirety of the fluid passing through flow line 10passes through one or more high shear devices operated in series or inparallel. In applications, flow line 10 is a vessel the use of whichcomprises contact with a fluid comprising an undesirable component or acomponent which may lead to formation of an undesirable component. Forexample, flow line 10 may be a boiler, a pump, a reflux drum, acondenser, or another vessel used to process a fluid for whichinhibition of an undesirable component or condition is desired.

Inhibition will occur whenever suitable conditions (e.g., time,inhibitor concentration, temperature, pressure, fluid composition)exist. In this sense inhibition could occur at any point in the flowdiagram of FIG. 1 if conditions are suitable. For example, injection ofdispersion comprising inhibitor into flow line 10 may serve to passivatethe surface of flow line 10 such that corrosion is avoided/ameliorated.In applications, the inhibitor interacts with an acid gas component ofthe fluid or carrier such that corrosion is avoided/ameliorated. Inembodiments, inhibitor injection prevents the formation of gas hydratesor ice within flow line 10. In embodiments, the inhibitor serves toinhibit scale formation within flow line 10. In applications, theinhibitor is a viscosity-reducing agent or antifreeze. Heat TransferDevices. Internal or external heat transfer devices for heating thefluid to be treated are also contemplated in variations of the system.For example, the fluid may be heated via any method known to one skilledin the art to help prevent ice or hydrate formation in addition to theuse of chemical inhibitor. Some suitable locations for one or more suchheat transfer devices are between pump 5 and HSD 40, between HSD 40 andflow line 10, and between flow line 10 and pump 5 when fluid in flowline 10 is used as carrier fluid. Some non-limiting examples of suchheat transfer devices are shell, tube, plate, and coil heat exchangers,as are known in the art.

Pumps. Pump 5 is configured for either continuous or semi-continuousoperation, and may be any suitable pumping device that is capable ofproviding controlled flow through HSD 40 and system 100. In applicationspump 5 provides greater than 202.65 kPa (2 atm) pressure or greater than303.975 kPa (3 atm) pressure. Pump 5 may be a Roper Type 1 gear pump,Roper Pump Company (Commerce Georgia) Dayton Pressure Booster Pump Model2P372E, Dayton Electric Co (Niles, Ill.) is one suitable pump.Preferably, all contact parts of the pump comprise stainless steel, forexample, 316 stainless steel. In some embodiments of the system, pump 5is capable of pressures greater than about 2026.5 kPa (20 atm). Inaddition to pump 5, one or more additional, high pressure pump (notshown) may be included in the system illustrated in FIG. 1. For example,a booster pump, which may be similar to pump 5, may be included betweenHSD 40 and flow line 10 for boosting the pressure into flow line 10.

Process for Introduction of Inhibitor into a Fluid to be Treated.Operation of high shear inhibitor injection system 100 will now bediscussed with reference to FIG. 1. In operation for the introduction ofan inhibitor into a fluid, an inhibitor to be dispersed is introducedinto system 100 via line 22, and combined in line 13 (or within HSD 40)with a fluid carrier.

The carrier may be the fluid to be treated or may be another fluidutilized to form the dispersion with the inhibitor which is subsequentlyinjected into the fluid to be treated, for example, via injection intoflow line 10 through which the fluid to be treated flows. The carriermay be a liquid or a gas. In embodiments, the carrier is a portion ofthe fluid to be treated. In embodiments, the carrier comprises liquidhydrocarbon. In embodiments, the carrier comprises LPG.

The inhibitor may be a gas or a liquid. In embodiments, inhibitor inline 22 comprises an inhibitor effective for inhibiting the productionof an undesirable component selected from ice, acidic components, scale,or flow reducers. In embodiments, the inhibitor is a corrosion inhibitorand interacts with acidic components of the fluid to be treated or acontact surface (e.g., interior wall) of flow line 10 such thatcorrosion of flow line 10 is minimized or prevented. Inhibitor maycomprise corrosion inhibitor effective for preventing/reducing corrosionof flow lines 10 due to a corrodent in a fluid that the flow linecontacts. For example, when flow line 10 carries a hydrocarbon fluidcomprising acid gas corrodents such as carbon dioxide, hydrogen sulfide,and/or hydrogen chloride in the presence of water, inhibitor 22 may beadded to the fluid to inhibit corrosion.

Generally, a corrosion inhibitor is a chemical compound that, when addedin small concentration, stops or slows down corrosion of metals andalloys. A desirable inhibitor may be selected as known to those of skillin the art. The inhibitors generally are applied in very small amounts,usually below 100 ppm, and more particularly in the range of from 5 toabout 50 ppm. A good corrosion inhibitor may provide 95% inhibition atconcentrations of 80 ppm, and 90% inhibition at concentrations of 40ppm. The corrosion inhibitor may function by effecting formation of athin film or passivation layer on a contact surface of flow line 10.This passivation layer may prevent access of the corrosive substance tothe material of the contact surface (e.g., metal). The so called“passivating” inhibitors (e.g., chromate) are frequently effective undervery extreme conditions. In embodiments, the disclosed system and methodare used to protect drill pipe through which drilling fluids containingthe corrodents are passed. In such embodiments, at least a portion ofthe carrier in line 21 may comprise the fluid to be treated. Thecorrosion inhibitor may inhibit either oxidation or reduction of theredox corrosion system (anodic and cathodic inhibitors). The corrosioninhibitor may scavenge dissolved oxygen. In applications, the corrosioninhibitor may provide a combination of two or more of these protectionmechanisms.

The corrosive component of the fluid to be treated may be one or more ofhydrogen sulfide, carbon dioxide, and sodium chloride. In embodiments,corrosion inhibitor in line 22 comprises hexamine, phenylenediamine,dimethylethanolamine, sodium nitrite, cinnamaldehyde, condensationproducts of aldehydes and amines (imines), chromates, nitrites,phosphates, hydrazine, ascorbic acid, and combinations thereof. Thesuitability of any given inhibitor for a certain application depends onthe material of the contact surfaces, the nature of the corrodents andother components of the fluid into which the inhibitors are added, andthe operating temperature.

In embodiments, the high shear system and method are used to amelioratereactive sulfur corrosion (e.g., from hydrogen sulfide), which may occurin either the liquid or vapor phase. In embodiments, high shear system100 is used to ameliorate naphthenic acid corrosion which tends to occurin liquid and in condensate phases and may be enhanced in high velocityregions.

U.S. Pat. No. 5,961,885 describes a corrosion inhibitor comprising adispersant, an imidazoline, an amide, an alkyl pyridine and a heavyaromatic solvent. The resultant blend effectively inhibits corrosion offlow lines containing low pH mixtures of hydrocarbons, water, and acidgases. In an embodiment, the inhibitor in line 22 is a corrosioninhibitor as described in U.S. Pat. No. 5,961,885 comprising adispersant, an imidazoline, an amide, an alkyl pyridine and a heavyaromatic solvent.

U.S. Pat. No. 5,188,179 describes methods for inhibiting corrosion inoil field pipe by continuously bringing reactants together in a fluidpassing through the pipe to form a precipitated film of iron disulfideon the interior wall of the pipe as an amorphous corrosion inhibitingcoating which is continuously being removed away and also beingcontinuously replenished by the continuing reaction of the reactants.The corrosion inhibiting film which is formed is a precipitate filmformed by the reaction of a polysulfide with ferrous iron. The ferrousiron may be a constituent of the fluid to be treated or separatelyintroduced. The polysulfide is the reaction product of hydrogen sulfideas a constituent existing in the passing fluid and an oxidizing agentsuch as ammonium nitrate which is separately introduced into the passingfluid. In embodiments, the inhibitor is a corrosion inhibitor comprisingan oxidizing agent which reacts with hydrogen sulfide in the carrier orcorrosive fluid to be treated to produce a polysulfide which then reactswith ferrous iron in the fluid to be treated to precipitate a corrosioninhibiting film on a contact surface of flow line 10.

The inhibitor may be a scale inhibitor which inhibits production ofscale in flow line 10. Scale deposits can occur in brine when thesolubility of the inorganic species in the brine decreases due tochanges in the pressure and/or temperature or upon mixing ofincompatible waters. Primary scales include sulfates (BaSO₄, CaSO₄,SrSO₄) and carbonates (CaCO₃, MgCO₃, FeCO₃). Carbonates can form in atransport line due to reduction of the system pressure, which reducesthe amount of carbon dioxide solubilized in the brine. Sulfates can formdue to mixing of incompatible brines (seawater and formation brine) orreduction of temperature, for example seawater injection into aformation with barium.

Scale inhibitors may be selected from sulfonated compounds, polymerbased inhibitors and phosphonates. In embodiments, the inhibitor maycomprise phosphine-polycarboxylate acid (PPCA) for the inhibition ofscale production. Typical dosage of scale inhibitor is about 5-100 ppm.

In embodiments, high shear system 100 is utilized for scale control in,for example, a transport flow line 10. Inhibitor may be injectedupstream of the point of scale risk. In embodiments, the injection ofscale inhibitor into flow line 10 via high shear device 40 is before orwhile the fluid is downhole. In embodiments, the injection of scaleinhibitor into flow line 10 is into or upstream a wax eater unit.

Inhibitor may be a hydrate inhibitor which minimizes or preventsproduction of hydrates (e.g., gas hydrates) in flow line 10. Theinhibitor may be an ice inhibitor, such as antifreeze whichprevents/minimizes production of ice and flow reduction in flow line 10.The inhibitor may be a viscosity reducer, which helps maintain flowwithin flow line 10.

The concentration of inhibitor will normally be correlated with theconcentration of reactant components in the fluid volume to be treated,for example, the concentration of acidic components in the fluid in flowline 10 Inhibitor in line 22 is intimately mixed, via high shear device40, with carrier in line 21. In applications, carrier in line 21comprises a slipstream drawn from flow line 10. In such instance, thecarrier is the same fluid as the fluid to be treated (e.g., line 21 andline 20 may be a single line). In alternative embodiments, the entiretyof fluid in flow line 10 is sent through one or more high shear mixers,in series or in parallel, to intimately mix the contents of flow line 10with inhibitor.

In embodiments, the inhibitor is fed directly into HSD 40, instead ofbeing combined with the carrier in line 13. Pump 5 may be operated topump the carrier through line 21, providing a controlled flow throughouthigh shear device (HSD) 40 and high shear system 100. Pump 5 may buildpressure and feed HSD 40. In some embodiments, pump 5 increases thepressure of the HSD inlet stream in line 13 to greater than 200 kPa (2atm) or greater than about 300 kPa (3 atmospheres). In this way, highshear system 100 may combine high shear with pressure to enhancereactant intimate mixing.

After pumping, the inhibitor and carrier are mixed within HSD 40, whichserves to create a fine dispersion of the inhibitor in the carrierfluid. In HSD 40, the inhibitor and carrier are highly dispersed suchthat nanobubbles, submicron-sized bubbles, and/or microbubbles ofgaseous inhibitor or nanodroplets, submicron-sized droplets, and/ormicrodroplets of liquid inhibitor are formed for superior dissolutioninto solution and enhancement of fluid mixing. For example, disperserIKA® model DR 2000/4, a high shear, three stage dispersing deviceconfigured with three rotors in combination with stators, aligned inseries, may be used to create the dispersion of inhibitor in fluidcarrier. The rotor/stator sets may be configured as illustrated in FIG.2, for example. The combined mixture of inhibitor and carrier may enterthe high shear device via line 13 and enter a first stage rotor/statorcombination. The rotors and stators of the first stage may havecircumferentially spaced first stage rotor teeth and stator teeth,respectively. The coarse dispersion exiting the first stage enters thesecond rotor/stator stage. The rotor and stator of the second stage mayalso comprise circumferentially spaced rotor teeth and stator teeth,respectively. The reduced bubble or droplet-size dispersion emergingfrom the second stage enters the third stage rotor/stator combination,which may comprise a rotor and a stator having rotor teeth and statorteeth, respectively. The dispersion exits the high shear device via line18. In some embodiments, the shear rate increases stepwiselongitudinally along the direction of the flow, 260.

For example, in some embodiments, the shear rate in the firstrotor/stator stage is greater than the shear rate in subsequentstage(s). In other embodiments, the shear rate is substantially constantalong the direction of the flow, with the shear rate in each stage beingsubstantially the same.

If HSD 40 includes a PTFE seal, the seal may be cooled using anysuitable technique that is known in the art. For example, carrier inline 21, fluid mixture in line 13, or fluid in flow line 10 may be usedto cool the seal and in so doing be preheated prior to entering highshear device 40.

The rotor(s) of HSD 40 may be set to rotate at a speed commensurate withthe diameter of the rotor and the desired tip speed. As described above,the high shear device (e.g., colloid mill or toothed rim disperser) haseither a fixed clearance between the stator and rotor or has adjustableclearance. HSD 40 serves to intimately mix the inhibitor and the carrierfluid. In some embodiments of the process, the transport resistance isreduced by operation of the high shear device such that the velocity ofthe reaction is increased by greater than about 5%. In some embodimentsof the process, the transport resistance is reduced by operation of thehigh shear device such that the velocity of the reaction is increased bygreater than a factor of about 5. In some embodiments, the velocity ofthe reaction is increased by at least a factor of 10. In someembodiments, the velocity is increased by a factor in the range of about10 to about 100 fold.

In some embodiments, HSD 40 delivers at least 300 L/h at a tip speed ofat least 4500 ft/min, and which may exceed 7900 ft/min (40 m/s). Thepower consumption may be about 1.5 kW. Although measurement ofinstantaneous temperature and pressure at the tip of a rotating shearunit or revolving element in HSD 40 is difficult, it is estimated thatthe localized temperature seen by the intimately mixed fluid is inexcess of 500° C. and at pressures in excess of 500 kg/cm ² undercavitation conditions. The high shear mixing results in dispersion ofthe inhibitor in micron or submicron-sized bubbles or droplets. In someembodiments, the resultant dispersion has an average bubble or dropletsize less than about 1.5 μm. Accordingly, the dispersion exiting HSD 40via line 18 comprises micron and/or submicron-sized droplets or gasbubbles. In some embodiments, the mean bubble or droplet size is in therange of about 0.4 μm to about 1.5 μm. In some embodiments, theresultant dispersion has an average bubble or droplet size less than 1μm. In some embodiments, the mean bubble or droplet size is less thanabout 400 nm, and may be about 100 nm in some cases. In manyembodiments, the dispersion is able to remain dispersed at atmosphericpressure for at least 15 minutes.

Once dispersed, the resulting gas/liquid or liquid/liquid dispersionexits HSD 40 via line 18 and feeds into flow line 10, as illustrated inFIG. 1. The contents of flow line 10 may be maintained at a specifiedreaction temperature using heating and/or cooling capabilities (e.g.,heaters) and temperature measurement instrumentation. Pressure in theflow line may be monitored using suitable pressure measurementinstrumentation, employing techniques that are known to those of skillin the art.

Conditions of temperature, pressure, space velocity and inhibitorinjection per volume of fluid to be treated may be calculated as knownto those of skill in the art. The use of high shear device 40 may allowfor better interaction and more uniform mixing of the inhibitor with thefluid to be treated and may therefore permit a reduction in the amountof inhibitor utilized, and/or an increase in possible throughout. Insome embodiments, the operating conditions of system 100 comprise atemperature of at or near ambient temperature. In embodiments, flow line10 is operated at or near atmospheric pressure.

Optionally, the product dispersion in line 18 may be further processedprior to entering flow line 10, if desired. In flow line 10, inhibitionof undesirable component or condition occurs or continues. For example,if inhibitor in line 22 is corrosion inhibitor, passivation of surfaceswithin flow line 10 may occur. In embodiments, the injection ofdispersion in line 18 into flow line 10 prevents ice formation, flowreduction, or scaling within flow line 10, as discussed hereinabove.Fluid in line 10 downstream of injection location 16 having been treatedwith inhibitor may proceed to flow along flow line 10.

Multiple Pass Operation. In the embodiment shown in FIG. 1, the systemis configured for single pass operation, wherein the treated fluidbeyond injection point 16 in line 10 continues along flow line 10. Insome embodiments, flow line 10 may comprise a vessel, such as a boiler.In such embodiments, it may be desirable to pass the contents of flowline 10, or a liquid fraction thereof, through HSD 40 during a secondpass. In this case, at least a portion of the contents of flow line 10may be recycled from flow line 10 and pumped by pump 5 into line 13 andthence into HSD 40. Additional inhibitor may be injected via line 22into line 13, or it may be added directly into the high shear device(not shown). In other embodiments, product stream beyond injectionlocation 16 may be further treated prior to a portion thereof beingrecycled to high shear device 40.

Multiple High Shear Mixing Devices. In some embodiments, two or morehigh shear devices like HSD 40, or configured differently, are alignedin series, and are used to further inhibit an undesirable component orcondition. In embodiments, a plurality of high shear mixers ispositioned along a transport or process flow line 10, whereby inhibitoris added at many locations 16 along the line via multiple high shearmixers. Operation of the mixers may be in either batch or continuousmode. In some instances in which a single pass or “once through” processis desired, the use of multiple high shear devices in series may also beadvantageous. For examples, in embodiments, the entirety of the fluidflow in flow line 10 is passed through multiple high shear devices 40 inserial or parallel flow such that all of the fluid in flow line 10 iscontacted with inhibitor via high shear. For example, in embodiments,outlet dispersion in line 18 is fed into a second high shear device.When multiple high shear devices 40 are operated in series, additionalinhibitor may be injected into the inlet feedstream of each device. Insome embodiments, multiple high shear devices 40 are operated inparallel, and the outlet dispersions therefrom are introduced into oneor more flow lines 10.

Features. The increased surface area of the micrometer sized and/orsubmicrometer sized inhibitor droplets or gas bubbles in the dispersionin line 18 produced within high shear device 40 may result in fasterand/or more complete inhibition of undesirable conditions or componentswithin flow line 10.

While the description has been given with respect to a systemincorporating inhibitor injection into a pipeline, it is to beunderstood that the disclosed system and method are applicable to theinjection of various inhibitors, including, but not limited to,inhibitors for the reduction of scale production, inhibitor for theprevention of gas hydrate formation, inhibitors for prevention ofcorrosion, injections of materials for enhancing the flow of transportstreams, for example, antifreeze, viscosity-reducers, and combinationsthereof. The inhibitor may be added as a solid, a liquid, or a gas andmay be mixed with a liquid or a gas carrier. For example, solidinhibitor in line 22 may be added to high shear device 40 where it isintimately mixed with carrier fluid introduced via line 21.

In embodiments, use of the disclosed process comprising reactant mixingvia external high shear device 40 allows use of reduced quantities ofinhibitor than conventional inhibition and/or increases the degree ofinhibition. In embodiments, the method comprises incorporating externalhigh shear device 40 into an established process thereby reducing theamount of inhibitor required to effect inhibition and/or enabling theincrease in production throughput from a process operated without highshear device 40. In embodiments, the disclosed method reduces operatingcosts/increases production from an existing process. Alternatively, thedisclosed method may reduce capital costs for the design of newprocesses.

Without wishing to be limited to a particular theory, it is believedthat the level or degree of high shear mixing may be sufficient toincrease rates of mass transfer and also produce localized non-idealconditions that enable reactions to occur that would not otherwise beexpected to occur based on Gibbs free energy predictions. Localized nonideal conditions are believed to occur within the high shear deviceresulting in increased temperatures and pressures with the mostsignificant increase believed to be in localized pressures. The increasein pressures and temperatures within the high shear device areinstantaneous and localized and quickly revert back to bulk or averagesystem conditions once exiting the high shear device. In some cases, thehigh shear mixing device induces cavitation of sufficient intensity todissociate one or more of the reactants into free radicals, which mayintensify a chemical reaction or allow a reaction to take place at lessstringent conditions than might otherwise be required. Cavitation mayalso increase rates of transport processes by producing local turbulenceand liquid micro-circulation (acoustic streaming). An overview of theapplication of cavitation phenomenon in chemical/physical processingapplications is provided by Gogate et al., “Cavitation: A technology onthe horizon,” Current Science 91 (No. 1): 35-46 (2006). The high shearmixing device of certain embodiments of the present system and methodsinduces cavitation whereby inhibitor and/or carrier fluid aredissociated into free radicals, which then react to provide inhibitionof undesirable components of a fluid or undesirable conditions in a flowline 10.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, and so forth). Use ofthe term “optionally” with respect to any element of a claim is intendedto mean that the subject element is required, or alternatively, is notrequired. Both alternatives are intended to be within the scope of theclaim. Use of broader terms such as comprises, includes, having, etc.should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,and the like.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present invention. Thus, the claims are a further description andare an addition to the preferred embodiments of the present invention.The disclosures of all patents, patent applications, and publicationscited herein are hereby incorporated by reference, to the extent theyprovide exemplary, procedural or other details supplementary to thoseset forth herein.

What is claimed is:
 1. A method for introducing inhibitor into a fluidto be treated, the method comprising: forming a dispersion comprisingdroplets, particles, or gas bubbles of inhibitor dispersed in acontinuous phase of a carrier, wherein forming the dispersion comprisessubjecting a mixture of the inhibitor and the carrier to a shear rate ofgreater than about 20,000 s⁻¹ in a high shear device comprising at leastone generator comprising a rotor and a complementarily-shaped stator,wherein the rotor and the stator each comprise grooves, wherein thegrooves of the rotor and the grooves of the stator of each generator aredisposed in alternating directions; and using at least a portion of thedispersion to inhibit corrosion.
 2. The method of claim 1, wherein thedroplets, particles, or gas bubbles have a mean diameter of less than 5μm, and wherein the dispersion is formed in a high shear device.
 3. Themethod of claim 2, wherein the mean diameter is less than 1 μm.
 4. Themethod of claim 2, wherein the fluid to be treated comprises boilerfeedwater or a transport stream comprising hydrocarbons.
 5. The methodof claim 1, wherein using at least a portion of the dispersion toinhibit corrosion further comprises injecting the dispersion into a gaswell, wherein the dispersion is formed from a liquid or solid inhibitor.6. The method of claim 1, wherein the dispersion is formed from agaseous inhibitor.
 7. The method of claim 1, wherein using thedispersion to inhibit corrosion further comprises treating an inner flowline surface.
 8. The method of claim 1, wherein using at least a portionof the dispersion to inhibit corrosion further comprises injecting thedispersion into a geothermal system, and wherein the carrier comprisesat least a portion of the fluid to be treated.
 9. The method of claim 1,wherein forming the dispersion further comprises rotating the at leastone rotor at a tip speed of at least 22.9 m/s (4,500 ft/min).
 10. Themethod of claim 9, wherein the carrier is LPG, and wherein the highshear device produces a local pressure of at least about 1034.2 MPa(150,000 psi) at the tip of the at least one rotor.
 11. A method forintroducing inhibitor into a fluid to be treated, the method comprising:processing a fluid mixture comprising inhibitor and a carrier fluid in ahigh shear device to produce a dispersion of inhibitor in the carrierfluid, wherein the high shear device comprises at least one generatorcomprising a rotor and a complementarily-shaped stator, and wherein therotor and the stator of each of the at least one generators eachcomprise grooves, wherein the grooves of the rotor and the grooves ofthe stator of each generator are disposed in alternating directions; andusing the dispersion to inhibit a component selected from the groupconsisting of ice, scale, hydrates, acidic chemicals, and combinationsthereof
 12. The method of claim 11, the method comprising operating thehigh shear device at a shear rate greater than 20,000 s⁻¹.
 13. Themethod of claim 11, wherein using the dispersion comprises treating asurface of a vessel or a flow line, wherein the dispersion comprisesparticles, droplets, or gas bubbles of inhibitor having an averagediameter of the droplets, particles, or gas bubbles less than about 5μm.
 14. The method of claim 13, wherein the vessel is a boiler.
 15. Amethod for introducing inhibitor into a fluid to be treated, the methodcomprising: forming a dispersion comprising droplets, particles, or gasbubbles of the inhibitor dispersed in a carrier fluid, wherein thedroplets, particles, or gas bubbles have a mean diameter of less than 5μm; subjecting the dispersion to a shear rate greater than 20,000 s⁻¹ ina high shear device, wherein the high shear device comprises at leastone generator comprising a rotor and a complementarily-shaped stator,wherein the rotor and the stator of each of the at least one generatorseach comprise grooves, and wherein the grooves of the rotor and thegrooves of the stator of each generator are disposed in alternatingdirections; and using the dispersion to treat a surface of a flow lineor vessel.
 16. The method of claim 15, wherein the rotor and the statorof each of the at least one generators are separated by a shear gapwidth that is the minimum distance between the rotor and the stator, andwherein the high shear device is configured to produce a tip speed ofthe rotor of greater than 22.9 m/s (4,500 ft/min).
 17. The method ofclaim 16, wherein the high shear device comprises at least twogenerators.